Refrigeration apparatus



Nov. 26, 1968 A. E. ARLEDGE, JR

REFRIGERATION APPARATUS 2 Sheets-Sheet 1 Filed Feb. 21, 1966 FIG.|

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INVENTOR. ARTHUR E. ARLEDGE JR ATTORNEY.

Nov. 26, 1968 A. E. ARLEDGE, JR

REFRIGERATION APPARATUS 2 Sheets-Sheet 2 Filed Feb. 21, 1966 INVENTOR. ARTHUR E. ARLEDGE, JR.

ATTORNEY.

United States Patent 3,412,569 REFRIGERATION APPARATUS Arthur E. Arledge, Jr., Springfield, N.J., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Feb. 21, 1966, Ser. No. 528,966 Claims. (Cl. 62-115) ABSTRACT OF THE DISCLOSURE A refrigeration machine having provision for low load operation which includes separate passageways connecting the condenser and evaporator, wherein the passageway for delivering refrigerant to the evaporator from the condenser includes a refrigerant distribution means assuring flow of refrigerant over the tube bundle in the evaporator to increase the efficiency of the machine at low load condition.

This invention relates broadly to refrigeration machinery. More particularly, this invention relates to arrangements for the distribution of liquid refrigerant within a refrigeration machine. Still more particularly, this invention relates to arrangements for distributing liquid refrigerant over a tube bundle in a refrigerant evaporator during periods When the pressure within the evaporator exceeds the pressure in the condenser.

In refrigeration machinery having relatively high tonnage capacity of the kind employed in air conditioning installations for the purpose of providing a continuous supply of chilled water, arrangements have been suggested for obtaining a refrigerating effect under circumstances where the normal pressure relationship between the high and low sides of the machine is temporarily reversed, due to an unusual variation in the operating cycle of the machine. For example, during certain months of the year, the ambient temperature may be drastically reduced during the evening or night-time hours in some geographic areas. If air cooled condensing equipment is employed in the refrigeration machine, the temperature and pressure within the condenser is drastically reduced below the normal operating range of condenser temperatures and pressures. At the same time, the evaporator pressure and temperature may remain within the normal operating range, due to the continual load on the machine during these hours. It has been proposed that a separate conduit be provided connecting the evaporator and the condenser, and that during the conditions described, this conduit be opened so that vaporous refrigerant in the evaporator may flow directly to the condenser, and thus bypass the compressor, the operation of which would be terminated in order to conserve power. The vapor introduced through the connection described is liquified and flows through the usual refrigerant metering mechanism to the evaporator by gravity.

One of the problems involved with operating a refrigeration machine in the manner described is the distribution of liquid refrigerant over the tube bundle disposed in the evaporator. It has been proposed that a separate pump be employed for the purpose of delivering liquid refrigerant from the pool in the evaporator beneath the tube bundle to a spray header disposed over the tube bundle. Such an arrangement involves additional cost.

The chief object of this invention is the provision of an improved liquid refrigerant distribution system in a refrigeration machine that may be operated without the compressor under certain abnormal temperature-pressure conditions.

Another object of the invention is the provision of a liquid refrigerant distribution system incorporating as a Patented Nov. 26, 1968 "ice part thereof the eliminators or baffles employed to separate entrained liquid dorplets from the vaporous refrigerant flowing to the compressor.

The objects of this invention are obtained with a liquid distribution arrangement that is employed in addition to the usual refrigerant flow control system which assures maximum wetting of all tubes in the tube bundle. When employed, the liquid distribution system would operate alternatively with that used to forward liquid refrigerant to the evaporator under normal operating conditions and would deliver refrigerant from a location above the tubes in the evaporator.

Other objects and features of the invention will be apparent upon a consideration of the ensuing specification and drawings in which:

FIGURE 1 is a somewhat schematic view of a refrigeration machine, certain parts of which are shown in section, equipped with the refrigerant distribution system serving as the subject of this invention.

FIGURE 2 is a side view, partly in section, of the evaporator and condenser units employed in the machine illustrated in FIGURE 1 with the liquid distribution systern being shown between the two units.

FIGURE 3 is a fragmentary view of a portion of the liquid distribution system shown generally in FIGURES 1 and 2.

FIGURE 4 is an enlarged end view, partly in section, of the liquid refrigerant distribution system.

FIGURE 5 is a modification of the invention showing a liquid refrigerant distribution system suitable for use in a refrigeration machine having both the condenser and evaporator disposed in a single shell.

Refrigeration machinery of the kind to which this in vention applies includes a motor-compressor unit 10, usually of the centrifugal type, arranged to forward compressed refrigerant to a condenser 12 of the shelland-tube type, where the refrigerant is liquified. The liquid refrigerant then passes through a liquid refrigerant metering system 14, usually a float valve actuated mechanism, where it passes to an evaporator 16 of the shell-and-tube type containing a tube bundle 18 arranged therein. A medium to be chilled, such as Water or brine, flows within the circuit including the evaporator tube bundle and one or more heat transfer units positioned within an enclosure to be air conditioned. The refrigerant vapor created in the evaporator as heat is absorbed vfrom the medium flowing within the tubes, passes through an eliminator section and enters the centrifugal compressor through a suction line 19 in a manner well known in the art.

As indicated above, certain operating conditions will be encountered which will temporarily cause the pressure in the condenser or high side of the machine to equal or be slightly less than the pressure in the evaporator. It is to be understood that in the refrigerant flow circuit described above, the condenser is disposed above the evaporator so that gravity flow between the two units will ensue. It will be appreciated that if the refrigeration machine can be operated without the compressor that considerable savings will result, even though the refrigeration effect may be relatively small. Usually when the condensing temperature is reduced below its normal operating range in the manner described above, the load on the evaporator is somewhat reduced, so that the relative low capacity of the machine during operation at this level will be suflicient to satisfy the demand on the evaporator.

A conduit 20 connects the evaporator and the condenser at a location remote from the position of the liquid refrigerant metering device 14 and serves to pass refrigerant vapor from the evaporator to the condenser under certain conditions to be later described. A hand operated valve member 22 is arranged in conduit 20 and positioned to prevent communication through conduit 20 during normal operating periods.

Referring more particularly to FIGURE 2, it will be noted that transverse wall 24 is arranged in the condenser and acts in the manner of a weir to collect refrigerant formed in the condenser for normal passage to the float valve mechanism 14 over the wall. Wall 24 assures the collection of a pool of liquid refrigerant in the condenser. Sump 26 receives liquid from the pool and has communicating therewith conduit 28, strainer 30 and conduit 32 leading into the evaporator. Valves 34 and 36 are provided to control flow of refrigerant from the sump to the evaporator through lines 28 and 32. Disposed within the evaporator and extending substantially throughout its axial extent is a header 38 in communication with conduit 32. The header 38 overlies a baflle or eliminator system 40 which in turn overlies tube bundle 18 in the evaporator 16. The baflles all are employed to separate droplets of liquid refrigerant entrained by the vapor flow to the suction line from the evaporator.

Also, disposed in the evaporators shown in FIGURE 4 are a pair of perforated plates 42 overlying the baffies 40. The plates 42 are connected by spaced gussets 44 to support members 46 connected to the ends of the baffle 40, as shown in FIGURE 4. Longitudinal slots 48 are disposed throughout header 38 and communicate with the continuous openings formed between the ends of the plate 42 and the upper part of the supports 46.

Considering the operation of the liquid distribution system, it will be appreciated that when the need for operation of the compressor is no longer required because of the temperature and presure relationship mentioned above, valve member 22 will be opened as will be valve members 34 and 36. At the same time, the motor-compressor 10 will be shut down. Liquid refrigerant present in the condenser flows via lines 28 and 32 to the header 38 in the evaporator. From the header 38 liquid refrigerant passes via openings 48 onto the baffles 40, as shown in FIGURES 3 and 4. The bafiies are so arranged that the refrigerants introduced over the surace thereof flows in small quantities, collecting eventually in the lower part 50 of the baffle structure. The portions 50 have, at the bottom apex thereof, spaced openings through which the liquid refrigerant falls by gravity onto the tube bundle located thereunder. The bafiie assembly is constructed so that the flow outwardly and downwardly is promoted. Also, the individual bafile members 41 are formed in the manner shown in FIGURE 3 with the lowermost part or section 50 resilient so as to assume the position shown in FIGURE 3 under the influence of the collected refrigerant accumulating therein. With valves 34 and 36 open, the liquid refrigerant formed in the condenser flows to the evaporator via header 38 bypassing the normal float valve mechanism 14. Flow of liquid refrigerant through the header 38 continues until the pressure conditions in the condenser rise to the point where the refrigerant vapor formed in the evaporator must be pumped to the condenser. At this point, valves 34, and 36, as well as valve 22, are closed, and operation through the normal refrigerant flow path is resumed. In other words, liquid refrigerant overflowing wall 24 would flow to the chamber housing the float valve mechanism 14 for distributing refrigerant to the evaporator under the tube bundle in the well known manner.

FIGURE illustrates an additional embodiment of the invention, and is particularly useful when the condenser and evaporator sections of the machine are enclosed within a single housing or shell 52. In machinery of this type, there is provided a partition 54 which separates the high pressure condenser 12 from the lower pressure evaporator 16. Under normal operating conditions, refrigerant collected in the condenser overflows weir 24' to a receiver or float valve chamber 14' for passage to the evaporator via passageway 60 communicating with the evaporator 16' at a location beneath the tube bundle 18. In the shell 52, there is provided a partition opening 58 under control of hand operated valve 60. During normal operation in the refrigeration machine, valve 60 is closed and the vapor refrigerant from the evaporator flows to the compressor, not shown, through an opening 64.

Arranged above the tube bundle 16' is a distribution tray 62 having openings 64' in the bottom thereof. The tray is coextensive with the tube bundle. A plurality of spaced chutes 65 are arranged to communicate with the tray and receive liquid refrigerant from conduits 66 communicating with the section of the condenser in which liquid refrigerant collects. Flow through lines 66 is controlled by valves 68 having the handles thereof projecting beyond housing for selective manipulation by an operator.

Considering the operation of the form of the invention illustrated in FIGURE 5, when it is determined that a motor-compressor unit may be shut down, valve 60' is opened as are the valves 68. Under these circumstances, the vapor created in the evaporator flows to the condenser through opening 58. The vapor in the condenser is changed to liquid and collects for flow through conduits 66 to the chutes 65. The chutes deposit the liquid refrigerant on the distribution tray from where it drains over the tube bundle in the manner illustrated in FIGURE 5.

With the arrangements shown, there is provided alternative liquid refrigerant flow paths in a refrigeration machine, in which liquid refrigerant is introduced in a manner determined by the operating cycle of the machine and under circumstances where efiicient heat transfer between the tube bundle and refrigerant in the evaporator is obtained.

While I have described a preferred embodiment of the invention, it will be understood the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1. A refrigerant machine comprising a condenser, an evaporator of the shell-and-tube type, a refrigerant metering means interposed between the condenser and the evaporator for passing liquid refrigerant to the evaporator, a compressor for receiving vaporous refrigerant from the evaporator and forwarding it to the condenser, means forming a separate passage for the flow of vaporous refrigerant from the evaporator directly to the condenser so as to bypass the compressor, means forming a second passage for the flow of liquid refrigerant from the condenser to the evaporator, liquid refrigerant distribution means overlying the tubes in the evaporator to receive liquid refrigerant flowing in the second passage for delivery over the tubes from a location thereabove, and valve means regulating refrigerant flow in the machine so that when liquid refrigerant flows in said second passage, vaporous refrigerant may pass directly to condenser through the separate passage means.

2. A refrigeration machine as described in claim 1 including a battle assembly arranged over the evaporator tube bundle for separating entrained liquid refrigerant from the vaporous refrigerant flowing to the compressor, wherein said liquid refrigerant distribution means includes a header for receiving liquid refrigerant and delivering it over the baffle assembly onto the tube bundle.

3. A refrigeration machine as described in claim 1 wherein said liquid refrigerant distribution means includes a relatively fiat pan having at least one opening in the bottom disposed above said tube bundle for delivering liquid refrigerant flowing in said second passage over the tube bundle.

4. The method of operating a refrigeration machine including a condenser, evaporator having a plurality of spaced tubes arranged therein and compressor connected to form a closed circuit for the flow of refrigerant consisting of the steps of (a) forwarding liquid refrigerant formed in condenser through a refrigerant metering device during operation of the machine within its normal operating range to assure a conventional high pressure zone and low pressure zone within the machine,

(b) varying the path of flow of the refrigerant from the condenser under certain operating conditions so that the liquid refrigerant enters the evaporator through a second passage independent of the refrigerant metering device, and

(c) distributing the liquid refrigerant flowing in said second passage over the tubes in the evaporator from a location above the tubes.

5. The method described in claim 4 wherein said dis- References Cited UNITED STATES PATENTS 2,791,105 5/1967 Aronson 62504 3,191,396 6/1965 Ruddock 62-219 10 3,242,689 3/1966 Chubb et al. 62-117 LLOYD L. KING, Primary Examiner. 

